Focusing Light in Biological Tissues by Time-Reversing Light Changhuei Yang, Prof of Electrical Engineering and Bioengineering Electrical Engineering and Bioengineering California Institute of Technology The reason we can’t see through our hands isn’t because our hands absorb light strongly. Instead, it is because our hands scatter light strongly. Interestingly, light scattering in tissues may look random but their trajectories are deterministic. As such, it is possible to create a situation where light scattered from a tissue will retrace their paths through the tissue. This can be accomplished by time-reversing a light field via optical phase conjugation. I will discuss our recent effort at using time-reversal approaches to focus light at high intensity within an optically thick piece of biological tissue (Nature Comm. 3, 925 (2012)). This work has the potential to enable greatly improved depth-penetration and resolution improvement for deep tissue optical imaging. It also opens up the possibility for performing incision-less laser surgery and precision cancer therapy. Prof. Yang joined Caltech in 2003. He is an Electrical Engineering and Bioengineering professor. He has received the NSF Career Award, the Coulter Foundation Early Career Phase I and II Awards, and the NIH Director's New Innovator Award. Discover Magazine included Prof. Yang as one of the top 20 scientists under 40 in their list of Best Brains in Science 2008.